Bealfeld's career includes more than 30 years on the Baltimore police force, the last five of which he spent as commissioner. During that time, the city has seen a 24 percent drop in overall gun crime and the fewest number of homicides in 35 years.

The commissioner attributed a lot of it to a change in culture, or what he called a grassroots level of activism.

During his tenure, he became known for his passionate language when addressing crime in the city. Bealefeld participated in his last community walk as commissioner in June.

"I won't miss the opportunity to talk about bad guys with guns. For five years, that's been the rallying cry of who to focus on first and what to get the community behind -- get everybody's attention galvanized behind that," he said during that walk.

No replacement has been named yet. Bealefeld said he's answered questions to help in the search, but he hasn't given any recommendations; however, he said he does have some advice.

"Find someone who feels like they're responsible for all of it -- not just part of it but all of it," he said.

The mayor has formed a search committee to find a replacement, looking inside and outside the department.